Josh Collmenter started on Opening Day this season, but the Diamondbacks announced after Friday’s game that he’s headed to the bullpen.

Collmenter had a 3.46 ERA in 28 starts and five relief appearances last season, but he has struggled to the tune of a 5.24 ERA over 12 starts this year. His velocity, which has never been a strength to begin with, is down a tick from where it was last year and he has already allowed 10 home runs in just 68 2/3 innings.

“We think Josh can be successful as a starter,” Hale said. “So maybe going back and doing this and giving him a little break (will help him) get his good stuff back and a spot will open up and he’ll get a chance.”

The Diamondbacks are calling up right-hander Allen Webster to take Collmenter’s spot in the rotation Saturday against the Giants. Acquired from the Red Sox in the Wade Miley deal over the winter, the 25-year-old got a late start on the season due to shoulder fatigue and has a 9.00 ERA and 24/12 K/BB ratio in 23 innings over five starts with Triple-A Reno.